a(5) from Joe K. Crump (joecr(AT)carolina.rr.com), Aug 29 2000, who reports that the next term is greater than 22185312344622607538702383625075608111920737991870030337.

a(6) > 5^434 and would be too large to include. This result comes from combining Joe K. Crump's algorithm with the observation that digitally balanced numbers in base 5 are all even and digitally balanced numbers in base 3 are even iff they are of even length. - Martin Fuller, Nov 27 2006